President Obama’s nomination of Goodwin Liu for the San Francisco-based 9th U.S. Circuit Court of Appeals is facing opposition from Republicans who say he is activist and outside the mainstream.

Liu’s confirmation hearing is scheduled for Friday, the New York Times reports. The brewing controversy “could be a harbinger for how a strongly liberal pick to succeed Justice John Paul Stevens would play out,” the newspaper says.

Liu, a law professor at the University of California at Berkeley, has supported affirmative action and same-sex marriage, the Times says. He also ruffled Republican feathers when he criticized Chief Justice John G. Roberts Jr. and Justice Samuel A. Alito Jr.

Opponents have targeted Liu’s liberal statements and writings, and criticized him for overlooking information in his first submission to the Senate Judiciary Committee. Supporters say Liu is open-minded, and conservatives are exaggerating his positions.